1. Field of the Invention
The present invention relates to a detection circuit, and in particular relates to a voltage detection circuit.
2. Description of the Related Art
FIG. 1 shows a conventional connection between circuit boards. Referring to FIG. 1, connection boards 14 are coupled between circuit boards 12 and 16 and transmit signals therebetween. To connect the circuit boards 12 and 16 with the connection boards 14, conductive films, such as anisotropic conductive adhesives, are disposed between the circuit boards 12 and 16 and the connection boards 14, and the connection boards 14 are mounted on the circuit boards 12 and 16.
As the design of the circuit boards 12 and 16 becomes more complicated, more lines are disposed on each board, thus, the distance between the lines is reduced. When the distance between the lines approaches the error limit due to certain factors, such as alignment errors, the lines on connection board 14 can not be aligned to the lines on the circuit boards 12 and 16.
FIGS. 2a and 2b are cross-sectional views along line V-V in FIG. 1. As shown in FIG. 2a, when the lines 142 and 144 of the connection board 14 are respectively aligned to the lines 122 and 124 of the circuit board 12, the lines 142 and 144 can be respectively electrically connected to the lines 122 and 124 through anisotropic conductive adhesives 122. However, when alignment errors between the lines 122 and 144 and the lines 142 and 144 occurs, the line 144 of the connection 14 is electrically connected to the line 122 of the circuit board 12, resulting in mis-connection.
To avoid mis-connection, a conventional detection method is used to detect the impedance of the line 142 of the connection board 14. When the line 142 of the connection board 14 is totally electrically connected to the line 122 of the circuit board 12, the line 142 has a maximum impedance. When the line 142 of the connection board 14 is not electrically connected to the line 122 of the circuit board 12, the line 142 has a minimum impedance.
Whether the line 142 is electrically connected to the line 122 or not can be determined by detecting the impedance of the line 142. It is noted that although the line 142 has a maximum impedance, the impedance is smaller for the entire connection board 14 and is not easily detected.